Changing layer pixel size but still locking to a grid.

SO what i mean by this is I would love to be able to draw a background on a layer with pixel size of 1 and on a new layer draw my charter on a pixel size of 2. Now I know you can already do this but when you increase the pixel size they dont lock to a grid and you have to manually line them up. if there is a way to make them lock to a grid like with size 1 please let me no and i will delete this post as wont be needed thanks!